The decision reverses a lower court finding that the plate numbers and metadata—including time and location—for millions of motorists were “investigative records” that the Los Angeles Police Department and Los Angeles County Sheriff’s Department were permitted to keep secret.

The lawsuit for a week’s worth of the records was initially brought by the American Civil Liberties Union and the Electronic Frontier Foundation, a digital privacy advocacy group.

“The court recognized the huge privacy implications of this data collection,” said Jennifer Lynch, the senior staff attorney for the EFF. “Location data like this, that’s collected on innocent drivers, reveals sensitive information about where they have been and when, whether that’s their home, their doctor’s office, or their house of worship.”

The LAPD records data from 1.2 million cars per week through the ALPRs on patrol cars and fixed on light stanchions, according to the court documents.

The lawsuit seeking the week’s worth of data was originally filed in 2012.

The state Supreme Court ruled that the release of the data would not jeopardize policing methods—though the raw data may have to be redacted to prevent illicit use of the personal information that could be revealed about individuals’ travel habits (that decision was remanded back down to the trial court).

“We hold that real parties’ process of ALPR scanning does not produce records of investigations, because the scans are not conducted as part of targeted inquiry into any particular crime or crimes,” they write. “We recognize that it may not always be an easy task to identify the line between traditional ‘investigation’ and the sort of ‘bulk’ collection at issue here. But wherever the line may ultimately fall, it is at least clear that real parties’ ALPR process fall on the bulk collection side of it.”

The decision will apparently carry over into other mass data collection—which could include body cameras, facial recognition cameras and other technologies, beyond ALPRs.

“The California Supreme Court recognized that California’s sweeping public records exemption for police investigations doesn’t cover mass collection of data by police, like the automated scanning of license plates in this case,” said Peter Bibring, director of police practices at the ACLU of Southern California. “The court also recognized that mere speculation by police on the harms that might result from releasing information can’t defeat the public’s strong interest in understanding how police surveillance impacts privacy.”